The script was one the weakest parts of the first movie, so Del Toro's presence or absence is not really relevant to that aspect of the film.
Where Del Toro is missed is with the direction and set design and overall aesthetic.
Having less money is also a pretty huge issue as well.
True, the story and writing/characterization was paper thin, but I found it enjoyable as a B-movie with a huge budget since the monster battles were so well done. It's more Del Toro's touch with that stuff that I fear the second film will miss completely. He always had an eye for showcasing monsters and action in a inventive way, largely due to his love and passion for the source materials.
And yea the budget issue will hurt the main draw of Pacific Rim, for sure.
For what it's worth, he's pretty active on Twitter and I do not believe he has acknowledged this trailer in any way.
Yeah, figured.